Lens barrel and optical apparatus including the same

ABSTRACT

A lens barrel includes lens units movable in an optical axis direction, a driving unit including an annular actuator in which an optical axis serves as a rotation center, a first cam cylinder disposed inwardly of the annular actuator and including a circular cylindrical base portion and a large-diameter portion, a second cam cylinder configured to drive at least one of the lens units by rotating at an outer-peripheral side of the large-diameter portion, and a rotation transmitting portion provided at the large-diameter portion and transmitting rotation of the first cam cylinder to the second cam cylinder, wherein, in a state in which the length of the lens barrel is shortest, a portion of the second cam cylinder and the rotation transmitting portion overlap in the optical axis direction a lens unit holding frame that is closest to an object side.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.12/848,932, filed on Aug. 2, 2010, which claims the benefit of JapanesePatent Application No. 2009-183427 filed Aug. 6, 2009, which are herebyincorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel and an optical apparatusincluding the lens barrel.

2. Description of the Related Art

Hitherto, an image taking lens used in an optical apparatus such as asingle-lens reflex camera is required to have advanced functions at ahigh zoom ratio (high magnification ratio) that exceeds 5×. For example,an image taking lens is required to have an autofocus function. From theviewpoints of increasing speed, silencing noise, and increasingprecision, an autofocus actuator is required to be an annularoscillating-wave motor that rotates around an optical axis. As otherfunctions, an image taking lens is required to have an image blurcorrecting mechanism for restricting image blur caused by hand shake.

In addition, for further increasing convenience, there is a demand forreducing the size of the entire lens barrel. In general, in order toobtain a high zoom ratio in a zoom lens, it is effective to increase amoving-out amount of a lens unit that is closest to an object side(hereunder referred to as the “first lens unit”). However, when anattempt is made to provide the aforementioned functions or to reduce thesize, the moving-out amount of the first lens unit cannot be made large.

Japanese Patent Laid-Open Nos. 2005-77425 and 2001-318292 each discuss alens barrel of a zoom lens whose zoom ratio is increased by moving out amoving-out mechanism of a first lens unit in two or more steps.

Japanese Patent Laid-Open No. 2005-77425 discusses a structure of thelens barrel in which the moving-out amount of the first lens unit ismade large by a first cam cylinder disposed inwardly of a firststationary cylinder, a second cam cylinder disposed inwardly of thefirst cam cylinder, and a cam groove provided at the inner periphery ofa first lens unit moving cylinder. In this structure, if the first camcylinder is rotated by a zoom operation, rotation is transmitted to thesecond cam cylinder by mutual action between a straight groove of thefirst cam cylinder and a roller provided at the second cam cylinder.

However, in the lens barrel discussed in Japanese Patent Laid-Open No.2005-77425, if an attempt is made to mount the aforementioned annularactuator as a driving unit of the lens unit, the length of the firstlens unit moving cylinder in the direction of an optical axis isrestricted. Therefore, a sufficient moving-out amount of the first lensunit moving cylinder cannot be easily provided. In addition, since a camcylinder 1 and a cam cylinder 2 are disposed inwardly of the stationarycylinder, if an attempt is made to mount the aforementioned image blurcorrecting mechanism, the image blur correcting mechanism needs to bedisposed in a narrow space situated inwardly of the cam cylinder 2. Thismakes it difficult to mount a mechanism that can provide a sufficientimage blur correction effect.

Japanese Patent Laid-Open No. 2001-318292 discusses a structure of thelens barrel in which the moving-out amount of a first unit cylinder ismade large by a first cam cylinder disposed outwardly of a stationarycylinder, a thrust ring disposed outwardly of the first cam cylinder,and a third cam cylinder rotatable relative to the thrust ring. In thisstructure, if the first cam cylinder is rotated by a zoom operation, itsrotation is transmitted to the third cam cylinder by mutual actionbetween a roller provided at an end of the first cam cylinder and astraight groove of the third cam cylinder.

However, even in the lens barrel discussed in Japanese Patent Laid-OpenNo. 2001-318292, if an attempt is made to mount the aforementionedannular actuator as a driving unit of the lens unit, the length of thethird cam cylinder in the direction of an optical axis is restricted.Therefore, a sufficient moving-out amount of the first unit cylindercannot be provided. In addition, if an attempt is made to provide asufficient moving-out amount of the first unit cylinder by increasingthe length of the third cam cylinder, the transmission of rotationbetween the first cam cylinder and the third cam cylinder is limited.Therefore, the movement amounts of the thrust ring and the third camcylinder cannot be made large. Consequently, when the cam cylinder 3 ismade longer towards an object side, the shortest overall lens length isincreased.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a lens barrelcomprising a plurality of lens units movable in a direction of anoptical axis; a driving unit including an annular actuator in which theoptical axis serves as a rotation center; a first cam cylinder disposedinwardly of the annular actuator, the first cam cylinder including acircular cylindrical base portion and a large-diameter portion, the baseportion rotating to drive at least one of the plurality of lens units,the large-diameter portion having an outside diameter that is largerthan that of the base portion, the large-diameter portion beingpositioned in an area differing from an area where the annular actuatoris disposed in the direction of the optical axis; a second cam cylinderconfigured to drive the at least one of the plurality of lens units as aresult of rotating at an outer-peripheral side of the large-diameterportion; and a rotation transmitting portion provided at thelarge-diameter portion, the rotation transmitting portion beingconfigured to transmit rotation of the first cam cylinder to the secondcam cylinder. In the lens barrel, in a state in which a length of thelens barrel is shortest, a portion of the second cam cylinder and therotation transmitting portion overlap a lens unit holding frame in thedirection of the optical axis or an end portion of the large-diameterportion is positioned between a lens unit holding frame and the secondcam cylinder so as to overlap a portion of the lens unit holding framein the direction of the optical axis, the lens unit holding frame beingdisposed closest to an object side.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a case in which the entire length of aninterchangeable lens of a single-lens reflex camera is shortest.

FIG. 2 is a sectional view of a case in which the entire length of theinterchangeable lens of the single-lens reflex camera is longest.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will hereunder bedescribed in detail with reference to the attached drawings.

A lens barrel according to the present invention includes a plurality oflens units (L1 to L4) that are movable in a direction of an opticalaxis, and a focus unit (driving unit) 121 including an annular actuatorin which the optical axis serves as a rotation center. In addition, thelens barrel includes a first cam cylinder 105 disposed inwardly of theannular actuator. The first cam cylinder 105 drives at least some of theplurality of lens units as a result of rotating by rotation force from azoom operating ring 126. The first cam cylinder 105 has a circularcylindrical base portion 105 a, disposed at an area overlapping theannular actuator in the direction of the optical axis, and alarge-diameter portion 105 b, disposed at an area that does not overlapthe annular actuator (different area) and having an outside diameterthat is larger than that of the base portion 105 a. At the outerperipheral side of the large-diameter portion 105 b, the lens barrelincludes a second cam cylinder 116 and a rotation transmitting portion(roller) 134. The second cam cylinder 116 rotates to drive some of theplurality of lens units. The rotation transmitting portion 134 isprovided at the large-diameter portion 105 b and transmits the rotationof the first cam cylinder 105 to the second cam cylinder 116.

In a state in which the length of the lens barrel becomes shortest, anend portion 105 d of the large-diameter portion 105 b of the first camcylinder 105 is formed so as to be positioned between a first unitholding frame 119 (lens unit holding frame) and a second straightcylinder 117 and so as to overlap a portion of the first unit holdingframe 119 in the direction of the optical axis.

In a state in which the length of the lens barrel is shortest, a portionof the second cam cylinder 116 and the rotation transmitting portion 134are formed so as to overlap in the direction of the optical axis thelens unit holding frame 119 that is closest to an object side. Inaddition, an image blur correcting mechanism is disposed inwardly of thefirst cam cylinder 105.

An optical apparatus according to the present invention includes thelens barrel having the above-described features.

FIGS. 1 and 2 are sectional views showing an internal structure of aninterchangeable zoom lens for a single-lens reflex camera (opticalapparatus) according to an embodiment of the present invention, andschematically showing a camera body 100 to which the internal structureof the interchangeable zoom lens is mounted.

FIG. 1 shows a case in which the entire length of the lens barrel of theinterchangeable zoom lens of the single-lens reflex camera is shortest,and in which the lens barrel is at a zooming position at a wide-angleend.

FIG. 2 shows a case in which the entire length of the lens barrel of theinterchangeable zoom lens of the single-lens reflex camera is longest,and in which the lens barrel is at a zooming position at a telephotoend.

First Embodiment

A lens barrel 1 according to the embodiment will hereunder be describedwith reference to FIGS. 1 and 2.

The lens barrel 1 according to the embodiment is removably mounted tothe camera body 100. The camera body 100 includes an image pickupelement 100 a. The camera body 100 also includes other members that arenot shown.

An interchangeable lens (image taking lens) of the lens barrel 1according to the embodiment is a zoom lens including four lens units,that is, a first lens unit L1 to a fourth lens unit L4 in that orderfrom the object side to an image side.

All of the first lens unit L1 to the fourth lens unit L4 move in thedirection of the optical axis when a zoom operation (zooming) isperformed. The second lens unit L2 moves in the direction of the opticalaxis during a focus operation.

The third lens unit L3 includes two partial lens units, that is, a 3 athlens unit L3 a and a 3 bth lens unit L3 b. Of these, the 3 bth lens unitL3 b positioned at the side of the image pickup element 100 a is animage stabilizing lens unit that, in addition to moving in the directionof the optical axis, moves in a direction orthogonal to the optical axisfor correcting image blur caused by, for example, hand shake.

A mount 101 has a bayonet portion for mounting to the camera body 100,and is secured to a stationary cylinder 102 with a screw. An exteriorring 103 is secured by interposing it between the mount 101 and thestationary cylinder 102. A guide cylinder 104 has a securing portionwith respect to the camera body 100 when the stationary cylinder 102 issecured with a screw.

A first cam cylinder 105 that can advance and retreat while rotatingaround an optical axis by a roller (not shown) during zooming is fittedto the outer periphery of the guide cylinder 104. By this, if the firstcam cylinder 105 rotates during zooming, a point of intersection of aguide groove of the guide cylinder 104 extending in the direction of theoptical axis and a cam groove of the first cam cylinder 105 moves.Rollers 107, 111, and 112 engage the intersection point.

In accordance with the movement of the intersection point, a third unitholding frame 106 that holds the third lens unit L3 can move in thedirection of the optical axis through the roller 107 that is secured tothe third unit holding frame 106 with a screw.

Similarly, in accordance with the movement of the intersection point, afourth unit moving cylinder 109 to which the fourth unit holding frame108 that holds the fourth lens unit L4 is secured can move in thedirection of the optical axis through the roller 111 that is secured tothe fourth unit moving cylinder 109 with a screw. Similarly, a firststraight cylinder 110 can move in the direction of the optical axisthrough the roller 112 that is secured to the first straight cylinder110 with a screw. By moving the first straight cylinder 110, a firstunit holding frame 119 is moved as described below.

An electromagnetic stop unit 113 including a stop driving unit and astop blade is secured to the third unit holding frame 106. In addition,a blur correcting unit 114 is held at a rear end of the third unitholding frame 106 through a roller 115. The blur correcting unit 114 isheld so that the 3 bth lens unit L3 b is drivable in the directionorthogonal to the optical axis of the shooting lens, and drives the 3bth lens unit L3 b by a driving unit including a magnet and a coil inthe direction orthogonal to the direction of the optical axis.

At the inner periphery of the first straight cylinder 110, a second camcylinder 116 is fitted by a related bayonet structure. The second camcylinder 116 is such that its position with respect to the firststraight cylinder 110 in the direction of the optical axis isrestricted, and such that rotation of the first cam cylinder 105 istransmitted through the rotation transmitting portion (roller 134), sothat the second cam cylinder 116 is rotatably fitted. The rotationtransmitting portion is a main feature of the present invention, and itsstructure will be described below.

The first straight cylinder 110 has a guide groove (straight groove)extending in the direction of the optical axis. The second cam cylinder116 has a cam groove. By this, when the second cam cylinder 116 rotates,a point of intersection of the straight groove of the first straightcylinder 110 and the cam groove of the second cam cylinder 116 moves. Inaccordance with the movement of the intersection point, the secondstraight cylinder 117 can move in the direction of the optical axisthrough a roller 118 secured to the second straight cylinder 117 with ascrew.

The first unit holding frame 119 that holds the first lens unit L1 issecured to the vicinity of an end of the second straight cylinder 117.By this, the first lens unit L1 moves in the direction of the opticalaxis. Contact portions of the second straight cylinder 117 and the firstunit holding frame 119 have the form of slopes extending in acircumferential direction.

Therefore, by rotating the first unit holding frame 119 and mounting itto the second straight cylinder 117, it is possible to arbitrarilyselect the position where the first unit holding frame 119 is mounted tothe second straight cylinder 117 in the direction of the optical axis.By this, it is possible to properly set the position of the first lensunit L1 in the direction of the optical axis, and to correctdisplacements of focus positions at a wide-angle end and at a telephotoend caused by manufacturing errors.

A bayonet portion is provided at the outer periphery of an end of thesecond straight cylinder 117, and a threaded portion is provided at theinner periphery of the second straight cylinder 117. Accessories, suchas a hood and a filter, are mountable to the bayonet portion and thethreaded portion.

A decorative ring 120 has, for example, the name of a lens printed toits front surface.

A focus unit 121 (driving unit) is disposed so that a mounting portion112 a of the roller 112 at the first straight cylinder 110 moves into alocation between the outer periphery of the first cam cylinder 105 andthe inner periphery of the focus unit 121, and is secured to the guidecylinder 104.

The focus unit 121 primarily includes a differential mechanism and anannular vibratory motor (annular actuator) rotating around the opticalaxis as center. The focus unit 121 performs an output operation inaccordance with a rotor rotation amount of the vibratory motor and arotation amount of a manual ring 122. What the annular vibratory motordrives is not limited to a focusing lens unit. The vibratory motor maymove any member among, for example, a zooming lens unit, an imagestabilizing lens, or a stop mechanism.

A connecting ring 123 is secured to the object side of the focus unit121. An encoder flexible substrate 124 having a gray code pattern formedthereon is adhered to the outer periphery of a protrusion extending inthe form of an arc. Further, a protrusion is provided in a phase inwhich the encoder flexible substrate 124 is not provided. A roller 125that engages the zoom operating ring 126 is secured to this protrusionwith a screw. By engaging the roller 125 with a groove provided in aperipheral direction of the zoom operating ring 126, only rotationaround the optical axis is possible while movement in the direction ofthe optical axis is prevented.

The zoom operating ring 126 has a vertical groove with which a zoom key(not shown), which is secured to the first cam cylinder 105 with ascrew, engages. This makes it possible to transmit rotation of the zoomoperating ring 126 to the first cam cylinder 105 through the zoom key.

A zoom rubber 127 is wound around the outer periphery of the zoomoperating ring 120. A cam groove is formed in a circular cylindricalportion of a focus cam cylinder 128 that holds a second unit holdingframe 130. A roller (not shown), which is secured to the outer peripheryof a roller connecting ring 129 and which is inserted in a press-fitstate into a hole of the first cam cylinder 105, engages the cam groove.A key extending from the focus cam cylinder 128 engages an outputportion of the focus unit 121 so as to rotate together with the outputportion of the focus unit 121.

The second unit holding frame 130 holding the second lens unit L2 issecured to the focus cam cylinder 128. By this, when the first camcylinder 105 rotates, the second unit holding frame 130 advances andretreats in the direction of the optical axis through the focus camcylinder 128. The advancing/retreating amount is determined by the totalof the advancing/retreating amount of the first cam cylinder 105 itselfand the amount of change in the direction of the optical axis of aroller engaging point provided at the first cam cylinder 105 thatengages the cam groove of the focus cam cylinder 128.

By an output from the focus unit 121, the focus cam ring 128 engages thefocus unit 121 so as to rotate together therewith through the key.Therefore, while rotating, the focus cam groove 128 advances andretreats in accordance with the amount of change in the direction of theoptical axis of the roller engaging point provided at the first camcylinder 105 that engages the cam groove of the focus cam cylinder 128.

In the interchangeable lens according to the embodiment, a displacementin a focus position caused by a change in the focal length during innerfocusing is mechanically compensated for in this way, so that the secondlens unit L2 advances and retreats in the direction of the optical axis.

A main substrate 131 is electrically connected to, for example, theelectromagnetic stop unit 113 and the blur correcting unit 114 through aflexible substrate (not shown), to perform various control operations.Through a contact block (not shown), secured to the mount 101 with ascrew and connected to the main substrate 131 through the flexiblesubstrate (not shown), communication with and power supply to the camerabody 100 are performed.

A back cover 132 cuts off harmful light by elastic coupling with themount 101. A protective rubber ring 133 is elastically coupled to theback cover 132.

In the lens barrel having the above-described structure, when the zoomoperating ring 126 is rotated, the first cam cylinder 105 is rotatedthrough the zoom key. Then, in accordance with the above-describedmechanism, the first lens unit L1 to the fourth lens unit L4 advance andretreat in the direction of the optical axis for performing zooming.

By driving the vibratory motor in the focus unit 121 duringauto-focusing, or, by rotating the manual ring 122 during manualfocusing, the focus cam cylinder 128 is rotated through the differentialmechanism in the focus unit 121. In accordance with the above-describedmechanism, it is possible to cause the second lens unit L2 held by thesecond unit holding frame 130 secured to the focus cam cylinder 128 toadvance and retreat, and to perform focusing.

In the lens barrel according to the embodiment, when the first camcylinder 105 rotates by rotation of the zoom operating ring 126, thefirst straight cylinder 110 moves in a straight line through the roller112. The rotation of the first cam cylinder 105 causes the second camcylinder 116 to rotate through the roller 134. Further, the movement ofthe first straight cylinder 110 in a straight line causes the second camcylinder 116 and the second straight cylinder 117, subjected to bayonetcoupling, to move.

At this time, the rotation of the second cam cylinder 116 causes thesecond straight cylinder 117 to move further in a straight line throughthe roller 118. By moving the second straight cylinder 117 in a straightline, the first unit holding frame 119 holding the first lens unit L1and integrated to the second straight cylinder 117 moves.

Next, a structure of the rotation transmitting portion (roller) 134 fortransmitting the rotation from the first cam cylinder 105 to the secondcam cylinder 116 and moving the first unit holding frame 119 isdescribed. This structure is a feature of the embodiment.

The first cam cylinder 105 has the circular cylindrical base portion 105a, the large-diameter portion 105 b whose outside diameter is largerthan that of the base portion 105 a, and a flange 105 c connecting thebase portion 105 a and the large-diameter portion 105 b. A portion ofthe base portion 105 a overlaps a portion of the focus unit 121 in thedirection of the optical axis. Here, the phrase “overlaps . . . in thedirection of the optical axis” means that, for example, when thedirection of the optical axis corresponds to an X coordinate axis, theyhave the same X coordinate. In other words, they are disposed side byside in a direction orthogonal to the direction of the optical axis.

In the direction of the optical axis, the large-diameter portion 105 bis positioned at an area differing from the portion (area) of the focusunit 121. The large-diameter portion 105 b is formed in such a mannerthat, when the entire length of the lens barrel is shortest, the endportion 105 d is positioned in a space, formed by the first unit holdingframe 119 and the second straight cylinder 117, so as to overlap aportion of the first unit holding frame 119 in the direction of theoptical axis.

Here, the state in which the entire length of the lens barrel isshortest corresponds to a state in which the distance from a lenssurface closest to the object side to an image pickup plane is shortestby zooming.

The roller 134 serving as the rotation transmitting portion is securedto the outer periphery of the end portion 105 d overlapping the firstunit holding frame 119 at the large-diameter portion 105 b of the firstcam cylinder 105 in the direction of the optical axis. The roller 134engages a vertical groove of the second cam cylinder 116 disposed at theouter periphery of the large-diameter portion 105 b.

In the embodiment, when the entire length of the lens barrel isshortest, a portion of the second cam cylinder 116 and a portion of thefirst straight cylinder 110 are also disposed so as to overlap a portionof the first unit holding frame 119 in the direction of the opticalaxis.

According to the above-described structure, compared to a related lensbarrel, even when an annular vibratory motor (annular actuator) ismounted, it is possible to ensure the transmission of rotation betweenthe first cam cylinder 105 and the second cam cylinder 116 whileproviding a sufficient moving-out amount of the first straight cylinder110.

Since the first straight cylinder 110 and the second cam cylinder 116can have sufficient lengths in the direction of the optical axis, it ispossible to provide a sufficient moving-out amount of the secondstraight cylinder 117. As a result, the moving-out amount of the firstlens unit L1 can be large, so that an image taking lens (zoom lens)having a high zoom ratio can be easily provided.

The focus unit 121 is positioned at an area outside an area where thefirst cam cylinder 105 and the second cam cylinder 116 overlap in thedirection of the optical axis. That is, the focus unit 121 is formed soas to overlap the first cam cylinder 105 at a position in the directionof the optical axis that is different from the area where the first camcylinder 105 and the second cam cylinder 116 overlap. Therefore, whileproviding a high zoom ratio, it is possible to easily provide a spacethat is large enough for movement in a direction orthogonal to theoptical axis for correcting image blur by the 3 bth lens unit L3 b.

Accordingly, according to the embodiment, the second cam cylinder andthe rotation transmitting portion, provided at the large-diameterportion of the first cam cylinder, are disposed so as to overlap thefirst lens unit in the direction of the optical axis when the entirelength of the lens barrel is shortest. This makes it possible to providea sufficiently large movement amount of the first lens unit byefficiently using space.

That is, it is possible to provide a lens barrel that has an annularactuator mounted thereto and that is easily reduced in size whilemaintaining a high zoom ratio.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2009-183427 filed Aug. 6, 2009, which is hereby incorporated byreference herein in its entirety.

1. A lens barrel comprising: a plurality of lens units movable in adirection of an optical axis; a driving unit including an annularactuator in which the optical axis serves as a rotation center; a firstcam cylinder including a circular cylindrical base portion disposedinside the annular actuator and configured to rotate so as to drive atleast one of the plurality of lens units, and a large-diameter portiondisposed closer to a lens unit holding frame closest to an object sidethan the base portion and having an outside diameter larger than anoutside diameter of the base portion; a second cam cylinder configuredto drive the lens unit holding frame closest to the object side as aresult of rotating at an outer-peripheral side of the large-diameterportion; and a rotation transmitting portion provided at thelarge-diameter portion, the rotation transmitting portion beingconfigured to transmit rotation of the first cam cylinder to the secondcam cylinder, wherein, when the lens barrel is shortest, the rotationtransmitting portion overlaps a part of the second cam cylinder on aside of an outer periphery of a part of the lens unit holding frameclosest to the object side.
 2. The lens barrel according to claim 1,wherein the first cam cylinder is rotated by rotating an operating ring.3. The lens barrel according to claim 1, wherein an image blurcorrecting mechanism is disposed inwardly of the first cam cylinder. 4.A lens barrel comprising: a plurality of lens units movable in adirection of an optical axis; a driving unit including an annularactuator in which the optical axis serves as a rotation center; a firstcam cylinder including a circular cylindrical base portion disposedinside the annular actuator and configured to rotate so as to drive atleast one of the plurality of lens units, and a large-diameter portiondisposed closer to a lens unit holding frame closest to an object sidethan the base portion and having an outside diameter larger than anoutside diameter of the base portion; a second cam cylinder configuredto drive the lens unit holding frame closest to the object side as aresult of rotating at an outer-peripheral side of the large-diameterportion, wherein, when the lens barrel is shortest, an end portion ofthe large-diameter portion overlaps a part of the second cam cylinder ona side of an outer periphery of a part of the lens unit holding frameclosest to the object side, and the end portion of the large-diameterportion is positioned between the part of the lens unit holding frameclosest to the object side and the part of the second cam cylinder. 5.The lens barrel according to claim 4, wherein the first cam cylinder isrotated by rotating an operating ring.
 6. The lens barrel according toclaim 4, wherein an image blur correcting mechanism is disposed inwardlyof the first cam cylinder.
 7. An optical apparatus comprising: an imagepickup element; and a lens barrel configured to guide light to the imagepickup element, wherein the lens barrel comprises: a plurality of lensunits movable in a direction of an optical axis; a driving unitincluding an annular actuator in which the optical axis serves as arotation center; a first cam cylinder including a circular cylindricalbase portion disposed inside the annular actuator and configured torotate so as to drive at least one of the plurality of lens units, and alarge-diameter portion disposed closer to a lens unit holding frameclosest to an object side than the base portion and having an outsidediameter larger than an outside diameter of the base portion; a secondcam cylinder configured to drive the lens unit holding frame closest tothe object side as a result of rotating at an outer-peripheral side ofthe large-diameter portion; and a rotation transmitting portion providedat the large-diameter portion, the rotation transmitting portion beingconfigured to transmit rotation of the first cam cylinder to the secondcam cylinder, wherein, when the lens barrel is shortest, the rotationtransmitting portion overlaps a part of the second cam cylinder on aside of an outer periphery of a part of the lens unit holding frameclosest to the object side.
 8. An optical apparatus comprising: an imagepickup element; and a lens barrel configured to guide light to the imagepickup element, wherein the lens barrel comprises: a plurality of lensunits movable in a direction of an optical axis; a driving unitincluding an annular actuator in which the optical axis serves as arotation center; a first cam cylinder including a circular cylindricalbase portion disposed inside the annular actuator and configured torotate so as to drive at least one of the plurality of lens units, and alarge-diameter portion disposed closer to a lens unit holding frameclosest to an object side than the base portion and having an outsidediameter larger than an outside diameter of the base portion; and asecond cam cylinder configured to drive the lens unit holding frameclosest to the object side as a result of rotating at anouter-peripheral side of the large-diameter portion, wherein, when thelens barrel is shortest, an end portion of the large-diameter portionoverlaps a part of the second cam cylinder on a side of an outerperiphery of a part of the lens unit holding frame closest to the objectside, and the end portion of the large-diameter portion is positionedbetween the part of the lens unit holding frame closest to the objectside and the part of the second cam cylinder.